Most of the fishermen that I know hate the hot summer doldrums, and as the air and water temperatures rise, the trout big and small retreat to their haunts in the deeper pools. Those that don't tuck themselves into the undercut banks, and refuse to expend energy by moving to take modest insects or fly offerings. The cooler temperatures of night provide for a little more feeding activity but for the dry fly fisherman, few opportunities are available except for 'Hoppers'!